This invention is directed to fibers, especially hydrocarbon fibers as well as nonwoven fabrics, sheets, and laminates made therefrom. The invention also relates to ethylene acrylic copolymer products and products made from blends of the copolymer with other fiber-forming polymers.
Many thermoplastic resins may be extruded to form fibers of the monofilament type (relatively large) and very fine denier fibers, especially in nonwoven products. The most commonly used thermoplastic resin for formation of the very fine fibers are polypropylene and polyester, although many other resins have been suggested. It has not been possible to prepare acceptable nonwoven fabrics, webs, mats, and the like from ethylene acrylic copolymers because the extruded copolymers, e.g., ethylene acrylates, due to their high melt strength do not attenuate well to fibers by conventional methods. Thermoplastic resins such as ethylene vinyl acetate copolymers have been used; however, the EVA type copolymers are stable only to about 450.degree. F. and are not useable to blend with polypropylene which has an optimum processing temperature in the range of 500-550.degree. F. The ethylene acrylic copolymers of the invention are stable up to about 610.degree. F. and are therefore suitable for blends with polypropylene for optimum temperature processing.
Small fiber diameters are important for producing many nonwoven applications due to the bacterial efficiency that small fibers produce. The linear low density polyethylene/ethylene acrylic copolymer blends of the invention may be formed into fibers having such small diameters around 4-12 microns in size.
The copolymers and blends of the invention are especially useful in nonwoven structures. Examples of applications of nonwoven materials are diaper interfacings, wound dressings, clothing, sanitary products, medical products, sheeting, drapes, disposable clothing, protective clothing, outdoor fabrics, industrial fabrics, netting, bagging, membranes, filters, rope, cordage, wiping cloths, synthetic papers and tissue papers, and other products. The copolymer and blend fibers, multifilaments, and other nonwoven structures of the invention exhibit improved properties such as softness and low bonding temperatures in comparison to other materials. They have good tenacity and exceptional elongation.
Stretch of fabrics and other nonwoven products made from the blends and copolymers of the invention are especially advantageous in certain applications such as clothing where it is important for the clothing to stretch rather than tear. Another likely application for the nonwoven products of these materials is form-fitting garments, drapes, and the like wherein it is necessary to stretch the fabric somewhat after it is positioned for its intended use.